Wave Driver介绍-3（Wave API waveOutSetVolume）

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1.1 定义及简要说明

函数waveOutSetVolume可以用来调整系统的音量，其定义如下：

MMRESULT WINAPI waveOutSetVolume(HWAVEOUT hwo, DWORD dwVolume);

其中，第一个参数HWAVEOUT hwo可以传入两种值，第一种是wave-out设备ID号，此时函数调整的是设备音量，第二种是Stream句柄，调整的是所指向的Stream的音量。

今天为这个地方晕乎乎了半天，最后还是写了点测试程序才搞懂，有关这个函数的具体使用方法及操作细节请看下面的验证过程。

注：

下面的代码实际上是一个应用程序中部分代码，有关该应用程序的源码可以从我的资源中下载，主界面如下：

1.2 给函数传入wave-out设备ID的验证

下面的代码实现了对设备音量进行调整的功能，对应上图中的Loud和Soft按键的功能。其中函数void CWaveAPI_TestDlg::OnBnClickedButton1()实现了将设备音量（0～0xffff ffff）增加0x1000的功能，也即Loud按钮的功能，而按钮Soft的功能由函数void CWaveAPI_TestDlg::OnBnClickedButton2()实现，每次点击该按钮设备音量将减少0x1000。

详细如下：

static DWORD g_dwWaveOutGain = 0;

void CWaveAPI_TestDlg::OnBnClickedButton1()

{

// TODO: Add your control notification handler code here

DWORD dwDeviceID = 0;

DWORD deDeviceGain = 0;

for (dwDeviceID = 0; dwDeviceID < waveOutGetNumDevs(); dwDeviceID++) {

NKDbgPrintfW(L"Device #%d/r/n", dwDeviceID);

waveOutSetVolume((HWAVEOUT)dwDeviceID, g_dwWaveOutGain);

waveOutGetVolume((HWAVEOUT)dwDeviceID, &deDeviceGain);

NKDbgPrintfW(L"/r/n dst 0x%8x, read 0x%8x/r/n", g_dwWaveOutGain, deDeviceGain);

if (g_dwWaveOutGain <= (0xffffffff - 0x1000))

g_dwWaveOutGain+=0x1000;

else

g_dwWaveOutGain = 0xffffffff;

}

void CWaveAPI_TestDlg::OnBnClickedButton2()

{

// TODO: Add your control notification handler code here

DWORD dwDeviceID = 0;

DWORD deDeviceGain = 0;

for (dwDeviceID = 0; dwDeviceID < waveOutGetNumDevs(); dwDeviceID++) {

NKDbgPrintfW(L"Device #%d/r/n", dwDeviceID);

waveOutSetVolume((HWAVEOUT)dwDeviceID, g_dwWaveOutGain);

waveOutGetVolume((HWAVEOUT)dwDeviceID, &deDeviceGain);

NKDbgPrintfW(L"/r/n dst 0x%8x, read 0x%8x/r/n", g_dwWaveOutGain, deDeviceGain);

if (g_dwWaveOutGain >= 0x1000)

g_dwWaveOutGain-=0x1000;

else

g_dwWaveOutGain = 0;

}

1.3 给函数传入Stream句柄的验证

下面的代码中包括下面三个函数：

int StringFormatToWaveFormatEx( WAVEFORMATEX *wfx, const TCHAR* szWaveFormat );

ULONG SineWave( void* pBuffer, ULONG ulNumBytes, WAVEFORMATEX *pwfx, double dFrequency );

void PlayBackSound(bool bLoud);

其中第一个函数StringFormatToWaveFormatEx实现了格式转换的功能。我们一般都习惯上使用形如“WAVE_FORMAT_1M08”的标记来表示wave in/out的格式，该函数完成在形如“WAVE_FORMAT_1M08”的标志和结构体WAVEFORMATEX之间进行等价转换的功能。

/* defines for dwFormat field of WAVEINCAPS and WAVEOUTCAPS */

#define WAVE_INVALIDFORMAT 0x00000000 /* invalid format */

#define WAVE_FORMAT_1M08 0x00000001 /* 11.025 kHz, Mono, 8-bit */

#define WAVE_FORMAT_1S08 0x00000002 /* 11.025 kHz, Stereo, 8-bit */

#define WAVE_FORMAT_1M16 0x00000004 /* 11.025 kHz, Mono, 16-bit */

#define WAVE_FORMAT_1S16 0x00000008 /* 11.025 kHz, Stereo, 16-bit */

#define WAVE_FORMAT_2M08 0x00000010 /* 22.05 kHz, Mono, 8-bit */

#define WAVE_FORMAT_2S08 0x00000020 /* 22.05 kHz, Stereo, 8-bit */

#define WAVE_FORMAT_2M16 0x00000040 /* 22.05 kHz, Mono, 16-bit */

#define WAVE_FORMAT_2S16 0x00000080 /* 22.05 kHz, Stereo, 16-bit */

#define WAVE_FORMAT_4M08 0x00000100 /* 44.1 kHz, Mono, 8-bit */

#define WAVE_FORMAT_4S08 0x00000200 /* 44.1 kHz, Stereo, 8-bit */

#define WAVE_FORMAT_4M16 0x00000400 /* 44.1 kHz, Mono, 16-bit */

#define WAVE_FORMAT_4S16 0x00000800 /* 44.1 kHz, Stereo, 16-bit */

typedef struct

{

WORD wFormatTag; // format type

WORD nChannels; // number of channels (i.e. mono, stereo...)

DWORD nSamplesPerSec; // sample rate

DWORD nAvgBytesPerSec; // for buffer estimation

WORD nBlockAlign; // block size of data

WORD wBitsPerSample; // number of bits per sample of mono data

WORD cbSize; // the count in bytes of the size of

// extra information (after cbSize)

} WAVEFORMATEX, *PWAVEFORMATEX, *LPWAVEFORMATEX;

接下来说第二个函数SineWave，它完成根据调用者传入的参数构建正选波数据到pBuffer的功能，可以省却我们解析wav文件的烦恼。

第三个函数PlayBackSound是今天的主角，它完成了创建Stream，并使用Stream播放音频的同时调整音量的功能。

详细的代码如下：

// 转换数据

int StringFormatToWaveFormatEx( WAVEFORMATEX *wfx, const TCHAR* szWaveFormat )

{

int iRet;

DWORD tr=true;

TCHAR channels,bits1,bits2;

ZeroMemory(wfx,sizeof(*wfx));

iRet = _stscanf ( szWaveFormat, TEXT("WAVE_FORMAT_%i%c%c%c"), &wfx->nSamplesPerSec, &channels, &bits1, &bits2 );

if( iRet != 4 )

{

NKDbgPrintfW( ( TEXT( "ERROR: %s not recognized/n" ), (LPWSTR)szWaveFormat ) );

NKDbgPrintfW(TEXT("Possible Cause: Supplied format not in the form of WAVE_FORMAT%%i%%c%%c%%c/n"));

tr = false;

goto Error;

}

wfx->wFormatTag = WAVE_FORMAT_PCM;

switch( channels )

{

case 'M':

case 'm':

wfx->nChannels=1;

break;

default:

wfx->nChannels=2;

}

switch( wfx->nSamplesPerSec )

{

case 1:

case 2:

case 4:

wfx->nSamplesPerSec=11025*wfx->nSamplesPerSec;

}

wfx->wBitsPerSample=(bits1-TEXT('0'))*10+(bits2-TEXT('0'));

wfx->nBlockAlign=wfx->nChannels*wfx->wBitsPerSample/8;

wfx->nAvgBytesPerSec=wfx->nSamplesPerSec*wfx->nBlockAlign;

Error:

return tr;

}

// 产生正选波数据

ULONG SineWave( void* pBuffer, ULONG ulNumBytes, WAVEFORMATEX *pwfx, double dFrequency )

{

double dPhase = 0.0;

double dAmplitude = 1.0;

char *pClear, *pClearEnd;

const double TWOPI = 2* 3.1415926535897931;

pClearEnd = (char*)pBuffer + ulNumBytes;

pClear = pClearEnd - ulNumBytes % 4;

while( pClear<pClearEnd )

{

*pClear = 0;

pClear++;

}

int nsamples = ulNumBytes / pwfx->nBlockAlign;

int i, m_t0 = 0;

int m_dSampleRate = pwfx->nSamplesPerSec;

double dMultiplier, dOffset, dSample;

if( pwfx->wBitsPerSample == 8 )

{

unsigned char * pSamples = (unsigned char *) pBuffer;

dMultiplier = 127.0;

dOffset = 128.0;

if( pwfx->nChannels == 1 )

{

for (i = 0; i < nsamples; i ++ )

{

double t = ((double) (i+m_t0)) / m_dSampleRate;

dSample = dAmplitude * sin( t*dFrequency* TWOPI + dPhase );

pSamples[i] = (unsigned char) (dSample * dMultiplier + dOffset);

}

else

{

for (i = 0; i < nsamples; i ++)

{

double t = ((double) (i+m_t0)) / m_dSampleRate;

dSample = dAmplitude * sin (t*dFrequency* TWOPI + dPhase);

pSamples[2*i] = (unsigned char) (dSample * dMultiplier + dOffset);

pSamples[2*i+1] = pSamples[2*i]; // replicate across both channels

}

else

{

short * pSamples = (short *) pBuffer;

const double dMultiplier2 = 32767.0;

const double dOffset2 = 0.0;

if( pwfx->nChannels == 1 )

{

for (i = 0; i < nsamples; i += 1)

{

double t = ((double) (i+m_t0)) / m_dSampleRate;

dSample = dAmplitude * sin (t*dFrequency* TWOPI + dPhase);

pSamples[i] = (short) (dSample * dMultiplier2 + dOffset2);

}

else

{

for (i = 0; i < nsamples; i ++)

{

double t = ((double) (i+m_t0)) / m_dSampleRate;

dSample = dAmplitude * sin( t*dFrequency* TWOPI + dPhase );

pSamples[2*i] = (short) (dSample * dMultiplier2 + dOffset2);

pSamples[2*i+1] = pSamples[2*i]; // replicate across both channels

}

m_t0 += i;

return ulNumBytes;

}

功能：

播放正选波声音文件

参数：

bLoud：调整播放声音增益

true：增大

false：减小

返回值：

无

void PlayBackSound(bool bLoud)

{

// TODO: Add your control notification handler code here

HWAVEOUT hwo = NULL;

WAVEFORMATEX wfx;

MMRESULT hr;

static HANDLE hEvent;

WAVEHDR wh;

char *data = NULL;

DWORD dwSeconds = 1;

double dFrequency = 440.0;

DWORD dwExpectedPlaytime, dwTime = 0;

DWORD dwSleepInterval = 50; //50 milliseconds

// ***********************************************************************

// 1. 初始化相关资源

// ***********************************************************************

// 初始化WAVEFORMATEX变量wfx

if (!StringFormatToWaveFormatEx(&wfx,TEXT("WAVE_FORMAT_2M16"))) {

NKDbgPrintfW(L"Convert Audio Format Failed!/r/n");

return ;

}

// 输出格式信息

NKDbgPrintfW(L"************************************/r/n");

NKDbgPrintfW(L"wfx.wBitsPerSample %d/r/n", wfx.wBitsPerSample);

NKDbgPrintfW(L"wfx.nChannels %d/r/n", wfx.nChannels);

NKDbgPrintfW(L"wfx.nSamplesPerSec %d/r/n", wfx.nSamplesPerSec);

NKDbgPrintfW(L"************************************/r/n");

hEvent = CreateEvent( NULL, FALSE, FALSE, NULL );

// 打开wave out设备

hr = waveOutOpen(&hwo, 0, &wfx, NULL,(DWORD)hEvent, CALLBACK_NULL);

if(hr != MMSYSERR_NOERROR)

{

NKDbgPrintfW(L"waveOutOpen failed! Error number 0x%x/r/n", hr);

return ;

}

// 分配buffer

data = new char[dwSeconds * wfx.nAvgBytesPerSec];

if (!data) {

NKDbgPrintfW(L"Out of memeory/r/n");

return ;

}

ZeroMemory(data, dwSeconds * wfx.nAvgBytesPerSec);

// 初始化wh（WAVEHDR）

ZeroMemory(&wh, sizeof(WAVEHDR));

wh.lpData = data;

wh.dwBufferLength = dwSeconds * wfx.nAvgBytesPerSec;

wh.dwLoops = 1;

wh.dwFlags = WHDR_BEGINLOOP | WHDR_ENDLOOP;

dwExpectedPlaytime = wh.dwBufferLength * 1000 / wfx.nAvgBytesPerSec;

// 创造声波

SineWave(wh.lpData, wh.dwBufferLength, &wfx,dFrequency );

// ***********************************************************************

// 2. 开始播放声音操作

// ***********************************************************************

// 调整Stream音量

DWORD deDeviceGain = 0;

waveOutSetVolume((HWAVEOUT)hwo, g_dwWaveOutGain);

waveOutGetVolume((HWAVEOUT)hwo, &deDeviceGain);

NKDbgPrintfW(L"Volume of device 0 successfully set to 0x%8x, previous 0x%8x/r/n", g_dwWaveOutGain, deDeviceGain);

if (bLoud) {

if (g_dwWaveOutGain <= (0xffffffff - 0x1000))

g_dwWaveOutGain+=0x1000;

else

g_dwWaveOutGain = 0xffffffff;

}else {

if (g_dwWaveOutGain >= 0x1000)

g_dwWaveOutGain-=0x1000;

else

g_dwWaveOutGain = 0;

}

// 准备buffer

hr = waveOutPrepareHeader(hwo, &wh, sizeof(WAVEHDR));

if(hr != MMSYSERR_NOERROR)

{

NKDbgPrintfW(L"waveOutPrepareHeader failed! Error number 0x%x/r/n", hr);

return ;

}

// 写入buffer

hr = waveOutWrite(hwo, &wh, sizeof(WAVEHDR));

while( (!(wh.dwFlags&WHDR_DONE)) && ( dwTime<dwExpectedPlaytime+1000) )

{

Sleep( dwSleepInterval );

dwTime += dwSleepInterval;

}

// ***********************************************************************

// 3. 销毁所有资源

// ***********************************************************************

NKDbgPrintfW(L"Destroy all the resource/r/n");

waveOutReset(hwo);

if(hr != MMSYSERR_NOERROR) {

NKDbgPrintfW(L"waveOutUnprepareHeader failed! Error number 0x%x/r/n", hr);

return ;

}

hr = waveOutUnprepareHeader(hwo,&wh,sizeof(WAVEHDR) );

if(hr != MMSYSERR_NOERROR) {

NKDbgPrintfW(L"waveOutUnprepareHeader failed! Error number 0x%x/r/n", hr);

return ;

}

waveOutClose(hwo);

if(hr != MMSYSERR_NOERROR) {

NKDbgPrintfW(L"waveOutUnprepareHeader failed! Error number 0x%x/r/n", hr);

return ;

}

if (data)

delete []data;

if( hEvent)

CloseHandle(hEvent);

}

前面提到，应用程序中有四个按钮，左边的两个按钮已经讲过，右边的两个按钮“Loud Stream”和“Soft Stream”的实现就是通过调用上面的函数PlayBackSound完成，这部分代码如下：

void CWaveAPI_TestDlg::OnBnClickedButton3()

{

PlayBackSound(true);

}

void CWaveAPI_TestDlg::OnBnClickedButton4()

{

// TODO: Add your control notification handler code here

PlayBackSound(false);

}